Simplifying isn't as simple as it sounds

Over the past month or so I've been consuming some information through various platforms about simplifying life, establishing good habits for myself and trying to enjoy the world more.
It's much easier said than done.
The plan has been to de-clutter my room as a start point and other areas of the house. Not made a lot of progress there so far.
I know I have some bad habits and I've been pretty successful (touch wood) so far in shaking off one of them, for the second time, but I guess I'm still in the danger zone.
I've been listening to the Minimalists podcasts since I watched their documentary which explains what minimalism is and how two guys changed from having lives of excess to, as they put it, living with less.
One idea that has stood out for me is that if you're trying to stop something then you need to stop surrounding yourself with it. I'm putting that idea into practice in one particular area.
There's no doubt that I must change things.
Why is it that the bad habits, or certainly unhelpful ones, stick to you like leeches and good habits slide off like you're made of teflon?
Recently I joined the gym and have so far made a good fist of going a few times a week. Small steps first. The gym is a place I don't feel comfortable in, there's still the 25 year old me inside that wants to look as good as most of the people I see in that place and he's hard to let go of.
In reality I can't be an extremely fit 25 year old ever. Not unless I invent, or come across, a time machine.
In a way it's hard to let go of that thought. I have a couple of restrictions that will make significant physical change in the gym difficult but hopefully over the next six months I can see some improvement.
I'm likely to move house some time in the new year so a bit of decluttering early on can only be a good thing. Undoubtedly I have plenty of 'things' I don't need, that don't give me any real joy or add value to life.
The biggest challenge I face is myself.
I was reading Mark Manson's book 'The Subtle Art Of Not Giving A F**k' and aside from being very easy to read he makes a lot of sense in his own un-subtle way.
Some time ago I faced what I'd call a major life hurdle and I let it beat me for quite a number of years. In the book he talks about challenges and how we respond to them. Some people face them head on, and come through them stronger. Others (like me) let themselves be overpowered and as a result find things like change difficult to navigate.
Here's to the first step towards making change a little easier....